html {
    font-size: 50px;
}
@copies: 15;
@media screen and (min-width: 320px) {
    html{
       font-size: 320px / @copies
    }
} 
@media screen and (min-width: 360px) {
    html{
       font-size: 360px / @copies
    }
}
@media screen and (min-width: 375px) {
    html{
       font-size: 375px / @copies
    }
}
@media screen and (min-width: 384px) {
    html{
       font-size: 384px / @copies
    }
}
@media screen and (min-width: 400px) {
    html{
       font-size: 400px / @copies
    }
}
@media screen and (min-width: 540px) {
    html{
       font-size: 540px / @copies
    }
}
@media screen and (min-width: 720px) {
    html{
       font-size: 720px / @copies
    }
}
@media screen and (min-width: 750px) {
    html{
       font-size: 750px / @copies
    }
}